Return-path: <linux-wireless-owner@vger.kernel.org>
Received: from he.sipsolutions.net ([78.46.109.217]:47703 "EHLO
	sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1758026Ab3BZUz1 (ORCPT
	<rfc822;linux-wireless@vger.kernel.org>);
	Tue, 26 Feb 2013 15:55:27 -0500
Message-ID: <1361912099.8440.21.camel@jlt4.sipsolutions.net> (sfid-20130226_215534_874685_9E7FE72F)
Subject: Re: 3.7.8/amd64 full interrupt hangs due to iwlwifi under big nfs
 copies out
From: Johannes Berg <johannes@sipsolutions.net>
To: Marc MERLIN <marc@merlins.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>, Larry.Finger@lwfinger.net,
	bhutchings@solarflare.com, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org
Date: Tue, 26 Feb 2013 21:54:59 +0100
In-Reply-To: <20130223061414.GA16883@merlins.org>
References: <20120715215935.GF24420@merlins.org>
	 <1342419529.3265.12217.camel@edumazet-glaptop>
	 <20120716151826.GA10586@merlins.org>
	 <1342455717.2830.14.camel@edumazet-glaptop>
	 <20130219040557.GB4778@merlins.org>
	 <1361251033.19353.120.camel@edumazet-glaptop>
	 <1361268221.8553.1.camel@jlt4.sipsolutions.net>
	 <1361290909.19353.140.camel@edumazet-glaptop>
	 <1361351538.8629.3.camel@jlt4.sipsolutions.net>
	 <1361351703.8629.5.camel@jlt4.sipsolutions.net>
	 <20130223061414.GA16883@merlins.org>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Sender: linux-wireless-owner@vger.kernel.org
List-ID: <linux-wireless.vger.kernel.org>

On Fri, 2013-02-22 at 22:14 -0800, Marc MERLIN wrote:
> On Wed, Feb 20, 2013 at 10:15:03AM +0100, Johannes Berg wrote:
> > On Wed, 2013-02-20 at 10:12 +0100, Johannes Berg wrote:
> > > On Tue, 2013-02-19 at 08:21 -0800, Eric Dumazet wrote:
> > > > On Tue, 2013-02-19 at 11:03 +0100, Johannes Berg wrote:
> > > > > On Mon, 2013-02-18 at 21:17 -0800, Eric Dumazet wrote:
> > > > > 
> > > > > > > chrome: page allocation failure: order:1, mode:0x4020
> > > > > > > Pid: 8730, comm: chrome Tainted: G           O 3.7.8-amd64-preempt-20121226-fixwd #1
> > > > > > > Call Trace:
> > > > > > >  <IRQ>  [<ffffffff810d5f38>] warn_alloc_failed+0x117/0x12c
> > > > > 
> > > > > > You could try to load iwlwifi with amsdu_size_8K set to 0 (disable)
> > > > > > 
> > > > > > It should hopefully use order-0 pages
> > > > > 
> > > > > It will, do that then, unfortunately it can't switch at runtime because
> > > > > it advertised this support to the access point or clients.
> > > > 
> > > > What are the drawbacks of setting amsdu_size_8K to 0 by default ?
> > > 
> > > We're discussing this now, the only downside would be that we couldn't
> > > receive 8k A-MSDUs. Thing is, practically nobody uses A-MSDU anyway, and
> > > even when I suspect the difference between 4k and 8k won't be huge.
> > 
> > OTOH, this affects the protocol, and when you really can't allocate any
> > order-1 pages you pointed out yourself that many other things also won't
> > work, so I'm not really sure it makes a big difference if we change the
> > driver?
> 
> That as an unscientific test, but when I did the NFS eats all my pages
> test using ethernet, my system didn't hang like it did with iwlagn.
> 
> So while the NFS code is definitely doing something wrong when it uses
> its default huge buffers, the e1000e code deals with it without hanging
> my system.
> 
> So thanks for trying to improve the iwlagn code to avoid those system
> lockups.

We'll be submitting a patch to make single pages default.

johannes